Commit graph

84 commits

Author SHA1 Message Date
Stefano Brivio
2e93cb6ed8 test/lib: Drop perf_report_append() from perf_report
It's not used anymore. While at it, fix the function name in the
comment to perf_report_append_js().

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-24 00:09:23 +02:00
Stefano Brivio
cff565a1f6 test/lib: Wait for DHCPv4 before starting DHCPv6 client in two_guests test
I'm not sure why, but dhclient hangs otherwise. This reflects what we
do in the passt_in_ns setup steps.

Eventually, this whole block could go away if we let pasta configure
this network namespace with --config-net.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-23 02:46:24 +02:00
Stefano Brivio
d1dbc4f992 test/lib: Wait for kernel to free up ports used by iperf3 before reusing them
If we start another server on the same port right away, we might fail
to bind the port. A small delay appears to be needed -- I'm not
entirely sure why at this point.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-22 16:54:09 +02:00
Stefano Brivio
856b04490a test/lib: Run also iperf3 clients in background, revert to time-based wait
Unfortunately, this partially counters recent efforts by David to
speed up these tests, but it looks like iperf3 clients don't reliably
terminate, in some rare cases I couldn't isolate yet.

For the moment being, reintroduce the time-based wait approach, now
using the configurable test duration, and terminate the servers at
the end of it, in case they're stuck. There's no point in keeping
the 'sleep 2' later, so drop that, and while at it, make sure that
the stuck servers have time to flush the JSON output before we use
it.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-22 16:54:09 +02:00
Stefano Brivio
df29ebfe02 test/perf: Disable periodic throughput reports to avoid vhost hang
It appears that if we run throughput tests with one-second periodic
reports, the sending side of the vhost channel used for SSH-based
command dispatch occasionally stops working altogether. I haven't
investigated this further, all I see is that output is truncated
at some point, and doesn't resume.

If we use gzip compression (ssh -C) this happens less frequently,
but it still happens, seemingly indicating the issue is probably
related to vhost itself.

Disable periodic reports in iperf3 clients. The -i options were
actually redundant, so remove them from both test files as well as
from test_iperf3().

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-22 16:54:09 +02:00
Stefano Brivio
9f8b783d4a test/lib: Wait on iperf3 clients to be done, then send SIGINT to servers
An iperf3 client might fail to send the control message indicating
the end of the test, if the kernel buffer doesn't accept it, and exit
without having sent it, as the control socket is non-blocking. Should
this happen, the server will just wait forever for this message,
instead of terminating.

Restore some of the behaviour that went away with the
"test: Rewrite test_iperf3" patch: instead of waiting on servers to
terminate, wait on the clients. When they are done, wait 2 seconds,
and then send SIGINT to the servers, which make them still write
out the JSON report before terminating.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-22 16:54:09 +02:00
Stefano Brivio
119bb265a3 test/lib: Restore IFS while executing directives in def blocks
If we don't, guest command dispatch will fail altogether, given that
we use cat(1) on the enter file, which contains spaces.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-22 16:54:09 +02:00
Stefano Brivio
b323e5f439 test: term: When checking if status line is a number, hide errors
We use the [ "$x" -eq "$x" ] syntax to check if $x is a number. The
behaviour is clearly implied by POSIX, but some shells might actually
report the (intended) error, and dash floods script.log with
"Illegal number" error messages. Hide them.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-14 20:49:08 +02:00
David Gibson
6f2db0e34b test: Move perf.js report file to $LOGDIR/web
The tests generate a performance report in $BASEPATH/perf.js and
hooks/pre-push copies it to the website.  To avoid cluttering the working
directory, instead put perf.js in $LOGDIR/web, since it's a test output
artefact.  Update hooks/pre-push to copy from its new location.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
4e9b50f7b6 test: Move video processing files to $STATEBASE
The asciinema video handling creates a number of temporary files (.uncat,
.start, .stop) which currently go into the source tree.  Put them in the
temporary state directory to avoid clutter.

The final processed output is now placed into test_logs/web/ along with the
corresponding .js file with links, since they're essentially test
artefacts.  hooks/pre-push is updated to look for those files in the new
location when updating the web site.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
d813660107 test: Move pidfiles and nsholder sockets into state directory
Currently they go in the passt source tree with a fixed names, which means
their presence can mess with subsequent test runs.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
b23adf7132 test: Store pcap files in $LOGDIR instead of /tmp
The capture files are more or less a different form of log output from the
tests, so place them in $LOGDIR.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
07aa24499e test: Move pause temporary file to state directory
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
1c36c8d3f8 test: Use paths in __STATEDIR__ instead of 'temp' and 'tempdir' directives
Instead of using the 'temp' and 'tempdir' DSL directives to create
temporary files, use fixed paths relative to __STATEDIR__.  This has two
advantages:
  1) The files are automatically cleaned up if the tests fail (and even if
     that doesn't work they're easier to clean up manuall)
  2) When debugging tests it's easier to figure out which of the temporary
     files are relevant to whatever's going wrong

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
54c5addeaa test: Move context temporary files to state dir
Currently the context command dispatch subsystem creates a bunch of
temporary files in $LOGDIR, which is messy.  Store them in $STATEDIR which
is for precisely this purpose.  The logs from each context still go into
$LOGDIR.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
e4ecb6d795 test: Move passt_test_log_pipe to state directory
We use this fifo to send messages to the information pane.  Put it in the
state directory so it doesn't need its own cleanup.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
8cb7d5b461 test: Create common state directories for temporary files
The test scripts create a bunch of temporary files to keep track of
internal state.  Some are made in /tmp with individual mktemp calls, some
go in the passt source directory, and some go in $LOGDIR.  This can
sometimes make it messy to clean up after failed test runs.

Start cleaning this up by creating a single "state" directory ($STATEBASE)
in /tmp for all the state or temporary files used by a single test run.
Clean it up automatically in cleanup() - except when DEBUG==1, because
those files can be useful for debugging test script failures.

We create subdirectories under $STATEBASE for each setup function, exposed
as $STATESETUP.  We also create subdirectories for each test script and
expose those to the scripts as __STATEDIR__.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
a9b18300b4 test: Remove unused variable FFMPEG_PID_FILE
FFPMPEG_PID_FILE is set (creating a temporary file), then never used.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 11:12:41 +02:00
David Gibson
4381278b7d test: Use new-style command issue for passt_in_ns tests
Put the pieces together to use the new style context based dispatch for
the passt_in_pasta tests.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
87a57156cf test: Use context system for two_guests tests
Now that we have all the pieces we need for issuing commands both into
namespaces and into guests, we can use those to convert the two_guests to
using only the new style context command issue.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
56e755ba11 test: Use context system for guest commands
Extends the context system in the test scripts to allow executing commands
within a guest.  Do this without requiring an existing network in the guest
by using socat to run ssh via a vsock connection.

We do need some additional "sleep"s in the tests, because the new
faster dispatch means that sometimes we attempt to connect before
socat has managed to listen.

For now, only use this for the plain "passt" tests.  The "passt_in_ns" and
other tests have additional complications we still need to deal with.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
a8a437abd6 test: Extend context system to run commands in namespace for pasta tests
Extend the context system to allow commands to be run in a namespace
created with unshare, and use it for the namespace used in the pasta tests.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
2f87265d8b test: Use new-style contexts for passt pane in the pasta and passt tests
Convert the pasta and passt tests to use new-style context execution
for the things that run in the "passt" frame.  Don't touch the
passt_in_ns or two_guests tests yet, because they run passt inside a
namespace which introduces some additional complications we have yet
to handle.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
d9b9c252cd test: Issue host commands via context for most tests
Convert most of the tests to use the new-style system for issuing commands
for all host commands.  We leave the distro tests for now: they use
the same pane for both host and guest commands which we'll need some more
things to deal with.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
c2f248588b test: Integration of old-style pane execution and new context execution
We're creating a system for tests to more reliably execute commands in
various contexts (e.g. host, guest, namespace).  That transition is going
to happen over a number of steps though, so in the meantime we need to deal
with both the old-style issuing of commands via typing into and screen
scraping tmux panels, and the new-style system for executing commands in
context.

Introduce some transitional helpers which will issue a command via context
if the requested context is initialized, but will otherwise fall back to
the old style tmux panel based method.  Re-implement the various test DSL
commands in terms of these new helpers.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
a32df9b6f4 test: Allow a tmux pane to watch commands executed in contexts
We're moving to a new way of the tests dispatching commands to running in
contexts (host, guest, namespace, etc.).  As we make this transition,
though, we still want the user to be able to watch the commands running
in a context, as they previously could from the commands issued in the
pane.

Add a helper to set up a pane to watch a context's log to allow this.  In
some cases we currently issue commands from several different logical
contexts in the same pane, so allow a pane to watch several contexts at
once.  Also use tail's --retry option to allow starting the watch before
we've initialized the context which will be useful in some cases.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
3c47b65a64 test: Context execution helpers
For the tests, we need to run commands in various contexts: in the host,
in a guest or in a namespace.  Currently we do this by running each context
in a tmux pane, and using tmux commands to type the commands into the
relevant pane, then screen-scrape the output for the results if we need
them.

This is very fragile, because we have to make various assumptions to parse
the output.  Those can break if a shell doesn't have the prompt we expect,
if the tmux pane is too small or in various other conditions.

This starts some library functions for a new "context" system, that
provides a common way to invoke commands in a given context, in a way that
properly preserves stdout, stderr and the process return code.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-13 05:32:00 +02:00
David Gibson
e5e10aff81 test: Rewrite test_iperf3
test_iperf3() is a pretty inscrutable mess of nested background processes.
It has a number of ugly sleeps needed to wait for things to complete.

Rewrite it to be cleaner:
  * Use the construct (a & b & wait) to run 'a' and 'b' in parallel, but
    then wait for them both to complete before continuing
  * This allows us to wait for both the server and client to finish, rather
    than sleeping
  * Use jq to do all the math we need to get the final result, rather than
    jq followed by some complicated 'bc' mangling

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-07 11:01:22 +02:00
David Gibson
29247d0db6 test: Parameterize run time for throughput performance tests
Currently all the throughput tests are run for 30s.  This is reflected in
both the actual parameters given to the iperf commands, but also in the
matching sleeps in test_iperf3.

Allow this to be adjusted more easily with a new parameter to test_iperf3.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
[sbrivio: Reflect new parameter in comment to test_iperf3()]
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-09-07 11:01:22 +02:00
David Gibson
5c13b511d9 test: Combine iperf3c and iperf3s into a single DSL command
These two commands in the DSL to run an iperf client and server are always
used together, and some of the parameters must match between them.  The
iperf3s must also be run more or less immediately after iperf3c, since
iperf3c will run a client in the background after a sleep and requires a
server to be running before it will work.

A bunch of things can be made cleaner if we make a single DSL command that
runs both sides of the test.  For now make the combined command work
exactly like the two commands together did, warts and all.

This does lose the ability for the DSL scripts to give additional options
to the iperf3 server, but we weren't using that anyway.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-07 11:01:22 +02:00
David Gibson
6caf9e368e test: Kill qemu by pidfile rather than ^C
Currently in at least some of the testcases we kill qemu processes we're
done with by issuing a Control-C to the tmux panel it's running in.  That
makes things harder as we try to move towards allowing "headless" testing
without tmux.

So, instead always use an explicit kill on a pid derived from a pidfile
for killing qemu.  Note that we don't need to remove the pidfiles
afterwards, because qemu does that itself when terminated.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-08-20 19:07:12 +02:00
David Gibson
69126d4d48 test: Use shutdown test for pasta
For the passt and passt_in_ns tests we have a "shutdown" testcase that
checks for any errors from the passt process we were using (including
valgrind warnings).  Do the same for pasta tests, so that we catch any
error codes from the pasta process.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-08-20 19:07:12 +02:00
David Gibson
9224af1494 test: Rename slightly misleading "valgrind" tests
The "valgrind" test cases are designed to pick up errors reported when
passt is running under valgrind.  But what it actually does is just kill
the passt process, then see if it had a non-zero exit code.  That means it
will equally well pick up any other problems which caused passt to exit
with an error status: either something detected within passt or as a result
of passt being killed by an unexpected signal.

The fact that the "valgrind" test is actually responsible for shutting down
the passt process is non-obvious and can lead to problems when selectively
running tests during debugging.

Rename the "valgrind" tests to "shutdown" tests and run it regardless of
whether we're using valgrind or not.  This allows us to remove an ugly
speacial case in the passt_in_ns teardown code.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-08-20 19:07:12 +02:00
David Gibson
2fa308ac6e test: Split setup/teardown functions for build and distro tests
Currently the build tests and distro tests share a common setup function.
That works for now, but changes we want to make will mean they need
slightly different setup, so split the setup functions in preparation.

Currently, neither build nor distro tests have any teardown function.
Again, future changes are going to mean we need to do some teardown, so
create some empty for now teardown functions in preparation.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-08-20 19:07:12 +02:00
David Gibson
a918e6c4fc test: Remove unused *_XTERM variables
The DEMO_XTERM and CI_XTERM variables defined in test/lib/term aren't used
anywhere.  Remove them.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-08-20 19:07:12 +02:00
David Gibson
4094cec7f7 tests: Clean up better after iperf tests
The iperf based test commands create a bunch of .bw and .pid files for
each iperf client and server.  The server side .bw files are cleaned
up afterwards, but the pid files are not, and none of the client side
files are cleaned up.  The latter doesn't really matter when the
client is run on ephemeral guests, but sometimes we run it in a
namespace that shares the filesystem with the host.

Clean up all of these files after the tests.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-22 19:42:18 +02:00
David Gibson
2d289ec711 tests: Use dhclient --no-pid for namespaces in two_guests tests
Before starting the guests, these tests configure addresses in a pasta
namespace using dhclient.  However, because it's a user namespace, it's
not running as "real" root and can't write to the dhclient pid file.
This doesn't stop it working, but causes an ugly error message which we
can avoid by using the --no-pid option.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-22 19:42:18 +02:00
David Gibson
d078a1113f tests: Remove unnecessary ^D in passt_in_ns teardown
teardown_passt_in_ns() sends a ^D to the NS pane, which appears to be
intended to terminate the nsenter running there, leaving the namespace.
However, we've also sent a ^D to the PASST pane which will exit the pasta
instance which created the namespace.  With the namespace destroyed the
nsenter in the NS pane will be killed, so it does not need to be exited
explicitly.

In fact sending the extra ^D can be harmful, since it will exit the shell
in which the nsenter was run, causing the whole pane to be closed.  That
can then mean that the "pane_wait NS" hangs indefinitely.  I believe this
will sometimes work, because there's a race between the various options
here, but it should be more reliable without the extra ^D.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-22 19:42:18 +02:00
David Gibson
70fcba542e tests: Fix detection of empty 'hout' responses in passt{,_in_ns} tests
The dhcp/passt and dhcp/passt_in_ns tests at least, and maybe others
use 'hout' commands that need to be able to detect empty output.
However, we don't set PS1, which means the screen-scraping logic which
detects this may not be reliable.  In addition, if the host is using a
recent bash, it will have bracketed paste mode enabled which will also
add escape codes which will mess up the empty output detection.

Set the prompt and disable bracketed paste mode from the passt and
passt_in_ns setups to avoid these problems.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-22 19:41:42 +02:00
Stefano Brivio
dc04902baa test: Drop further ^D in passt demo teardown
Similar case as the one fixed by David's patch "tests: Remove
unnecessary ^D in passt_in_ns teardown": we happen to pseudo-randomly
close panes by unnecessarily exiting the parent shells there, and
subsequent pane_wait directives hang.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-07-22 19:41:42 +02:00
David Gibson
a832a44e67 tests: Explicitly list test files in test/run, remove "onlyfor" support
Currently test/run uses wildcards to run all of the tests in a directory.
However, that wildcard list is filtered down by the "onlyfor" directives
in the test files... usually to a single file.

Therefore, just explicitly list the files we *really* want to run for this
test mode.  This makes it easier to see at the top level what tests will
be executed, and to change that list temporarily while debugging specific
failures.

This means the "onlyfor" directive no longer has any purpose, and we can
remove it.  "onlyfor" was also the only used of the $MODE variable, so we
can remove that too.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-14 01:32:42 +02:00
David Gibson
544f790bf8 tests: Don't automatically traverse directories of test files
The top level listing control of which tests to run is in test/run, however
it uses the test() function which runs an entire directory of test files,
filtered by some criteria.  This makes it awkward to narrow down to a
subset of tests when debugging a specific failure.

To make this easier, have test() take an explicit list of test files to
run, and have the caller in test/run handle the directory traversal.  The
construct we use for this is pretty awkward to handle the fact that we're
in the source tree root directory rather than test/ at this point in
test/run.  Later cleanups will improve that.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-14 01:32:42 +02:00
David Gibson
5d7688d26f tests: Remove not-very-useful "req" directive
The test scripts support a "req" directive which requires one test script
to be run before another.  It's implemented by doing a topological sort
based on these directives in the runner scripts, which is about as awkward
as you'd expect in Bourne shell.

It turns out we only use this functionality in one place - to make the
"make install" test run after the plain "make" test.  We also already have
a simpler way of making sure tests run in a specific order: just put them
into the same test script file.

So, remove support for the "req" directive and just fold the build/all and
build/install test scripts together.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-14 01:32:42 +02:00
David Gibson
eb2e86dec0 tests: Remove unused set_mode() function
This utility function is never called.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-14 01:32:42 +02:00
David Gibson
2297637251 tests: Move mbuto download and execution to asset build
Move the download of mbuto and using it to create a sample initramfs to
the asset build makefile, rather than embedding it in the test scripts
themselves.

The two_guests tests used to use two separate copies of the mbuto
image.  As an initramfs the mbuto image is strictly readonly though,
so that's not necessary.  So, also use the same image for both guests.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-14 01:32:42 +02:00
David Gibson
db551e5de0 tests: Introduce makefile for building test assets
A number of passt/pasta testcases have initial steps which are just about
building images or other assets we need for the test proper.  Repeating
these for each test run can be quite costly.

This patch makes a start on moving this sort of test asset building to
a separate phase before running the tests proper.  For now just add a
Makefile to handle the asset building (although it doesn't build
anything yet), and make the path where we'll be building the assets
available to the tests.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-14 01:32:42 +02:00
David Gibson
7bcc5930a6 Invoke specific qemu-system-* binaries
A lot of tests and examples invoke qemu with the command "kvm".  However,
as far as I can tell, "kvm" being aliased to the appropriate qemu system
binary is Debian specific.  The binary names from qemu upstream -
qemu-system-$ARCH - also aren't universal, but they are more common (they
should be good for both Debian and Fedora at least).

In order to still get KVM acceleration when available, we use the option
"-M accel=kvm:tcg" to tell qemu to try using either KVM or TCG in that
order

A number of the places we invoked "kvm" are expecting specifically an x86
guest, and so it's also safer to explicitly invoke qemu-system-x86_64.

Some others appear to be independent of the target arch (just wanting the
same arch as the host to allow KVM acceleration).  Although I suspect there
may be more subtle x86 specific options in the qemu command lines, attempt
to preserve arch independence by using $(uname -m).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-07-14 01:32:42 +02:00
Stefano Brivio
20c418f1f9 test: Add external mbuto profile, drop udhcpc, and switch to it
This depends on a future change in mbuto to accept external profile
files. Add a file defining what we need for tests and demos, dropping
udhcpc and script as they're not needed anymore, and switch to it.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-07-06 08:09:26 +02:00
David Gibson
e48373382f Use dhclient instead of udhcpc
For some reason, the passt/pasta tests and examples use dhclient for
DHCPv6, but in most cases use udhcpc for DHCPv4.  Change it to use dhclient
for both DHCPv4 and DHCPv6.  This means one less tool we need for testing,
plus dhclient is easily available on Fedora whereas udhcpc is not.

Note that the passt tests still rely on udhcpc indirectly because mbuto
wants to put it into the guest images it generates.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-06-15 09:38:10 +02:00
David Gibson
ca0c33ae5b Tweak dhclient arguments for readability
A number of tests and examples use dhclient in both IPv4 and IPv6 modes.
We use "dhclient -6" for IPv6, but usually just "dhclient" for IPv4.  Add
an explicit "-4" argument to make it more clear and explicit.

In addition, when dhclient is run from within pasta it usually won't be
"real" root, and so will not have access to write the default global pid
file.  This results in a mostly harmless but irritating error:
    Can't create /var/run/dhclient.pid: Permission denied
We can avoid that by using the --no-pid flag to dhclient.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-06-15 09:38:10 +02:00