What is the significance of -- in the command line of commands like lxc-create or lxc-start.
I tried to use Google in order to get an answer but without success.
// Example 1
lxc-create -t download -n u1 -- -d ubuntu -r DISTRO-SHORT-CODENAME -a amd64
// Example 1
application="/root/app.out"
start="/root/lxc-app/lxc-start"
$start -n LXC_app -d -f /etc/lxc/lxc-app/lxc-app.conf -- $application &
As explained in the references provided in the comments, the "--" indicates the end of the options passed to the command. The following parameters/options will be eventually used by a sub-command called by the command.
In your example:
lxc-create -t download -n u1 -- -d ubuntu -r DISTRO-SHORT-CODENAME -a amd64
lxc-create command will interpret "-t download -n u1" and the remaining "-d ubuntu -r DISTRO-SHORT-CODENAME -a amd64" will be passed to the template script which will configure/populate the container.
In this specific example, the "-t download" makes lxc-create run a template script named something like "/usr/share/lxc/templates/lxc-download" to which it will pass "-d ubuntu -r DISTRO-SHORT-CODENAME -a amd64".
Related
Suppose i've got a zip file available under some URL. I need to get its hash, which should be identical to the one output by nix-prefetch-url --unpack <URL>, but without a working Nix installation. How can one do it?
Seems there is no easy way, as nix-prefetch-url adds the file to the store. More details here: https://discourse.nixos.org/t/generate-a-file-hash-similar-to-the-one-output-by-nix-prefetch-url/19907 (many thanks to prompt and thorough community member's response)
Use Docker.
Demo:
$ nix-prefetch-url --unpack https://github.com/hraban/git-hly/archive/06ff628d5f2b02d1a883c94b01d58187d117f4f3.tar.gz
path is '/nix/store/gxx1pfp19s3a39j6gl0xw197b4409cmp-06ff628d5f2b02d1a883c94b01d58187d117f4f3.tar.gz'
164gyvpdm6l6rdvn2rwjz95j1jz0w2igcbk9shy862sdx2rdw9hn
$ # Or .zip: it's the same, because of --unpack:
$ nix-prefetch-url --unpack https://github.com/hraban/git-hly/archive/06ff628d5f2b02d1a883c94b01d58187d117f4f3.zip
path is '/nix/store/1bpjlzknnmq1x3hq213r44jwag1xkaqs-06ff628d5f2b02d1a883c94b01d58187d117f4f3.zip'
164gyvpdm6l6rdvn2rwjz95j1jz0w2igcbk9shy862sdx2rdw9hn
Download to a local directory
$ cd "$(mktemp -d)"
$ curl -sSL --fail https://github.com/hraban/git-hly/archive/06ff628d5f2b02d1a883c94b01d58187d117f4f3.tar.gz | tar xz
$ cd *
And test it:
$ # Using the modern nix command:
$ nix hash path --base32 .
164gyvpdm6l6rdvn2rwjz95j1jz0w2igcbk9shy862sdx2rdw9hn
$ # Or the same, using nix-hash:
$ nix-hash --type sha256 --base32 .
164gyvpdm6l6rdvn2rwjz95j1jz0w2igcbk9shy862sdx2rdw9hn
Same in Docker:
$ docker run --rm -v "$PWD":/data nixos/nix nix --extra-experimental-features nix-command hash path --base32 /data
164gyvpdm6l6rdvn2rwjz95j1jz0w2igcbk9shy862sdx2rdw9hn
$ docker run --rm -v "$PWD":/data nixos/nix nix-hash --type sha256 --base32 /data
164gyvpdm6l6rdvn2rwjz95j1jz0w2igcbk9shy862sdx2rdw9hn
P.S.: I'm not a huge fan of nix-prefetch-url's default output (base32). The default output of nix hash path is better, if you can use it:
$ nix hash path .
sha256-FibesuhNC4M81Gku9qLg4MsgS/qSZ2F3y4aa2u72j5g=
$ # Sanity check:
$ nix-hash --type sha256 --to-base32 $(<<<"FibesuhNC4M81Gku9qLg4MsgS/qSZ2F3y4aa2u72j5g=" base64 -d | hexdump -v -e '/1 "%02x"' )
164gyvpdm6l6rdvn2rwjz95j1jz0w2igcbk9shy862sdx2rdw9hn
I have the need to start a java rest server with concourse that lives on an Ubuntu 18.04 machine. The version of concourse my company uses is 5.5.11. The server code is written in Java, so a simple java -jar <uber.jar> suffices from the command line (see below). In production, I will not have this simple luxury, hence my question.
I have an scp command working that copies the .jar from concourse to the target Ubuntu machine:
scp -i /tmp/key.p8 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null ./${NEW_DIR}/${ARTIFACT_NAME}.${ARTIFACT_FILE_TYPE} ${SRV_ACCOUNT_USER}#${JAVA_VM_HOST}:/var/www
Note that my private key is passed with -i and I can confirm that is working.
I followed this other SO Q&A that seemed to be promising: Getting ssh to execute a command in the background on target machine
, but after trying a few permutations of the suggested solution and other answers, I still don't have my rest service kicked off.
I've tried a few permutations of this line in my concourse script:
ssh -f -i /tmp/pvt_key1.p8 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null ${SRV_ACCOUNT_USER}#${JAVA_VM_HOST} "bash -c 'nohup java -jar /var/www/${ARTIFACT_NAME}.${ARTIFACT_FILE_TYPE} -c \"/opt/testcerts/clientkeystore\" -w \"password\" > /dev/null 2>&1 &'"
I've tried with and without the -f and -t switches in ssh, with and without the file stream redirection, with and without nohup and the Linux background ('&') command and various ways to escape the quotes.
At the bash prompt, this line successfully starts my server. The two switches are needed to point to the certificate and provide the password:
java -jar rest-service.jar -c "/opt/certificates/clientkeystore" -w "password"
I really think this is possible to do in Concourse, but I'm stuck at this point.
After a lot of trial an error, it seems I needed to do this:
ssh -f -i /tmp/pvt_key1.p8 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null ${SRV_ACCOUNT_USER}#${JAVA_VM_HOST} "bash -c 'sudo java -jar /var/www/${ARTIFACT_NAME}.${ARTIFACT_FILE_TYPE} -c \"/path/to/my/certificate\" -w \"password\" > /var/www/log.txt 2>&1 &'"
The key was I was missing the 'sudo' portion of the command. Using nohup as opposed to putting in a Linux bash background indicator ('&') seems to give me an error in the pipeline. This works for me, but others are welcome to post responses with better answers or methods that might be a better practice.
I have the below command
su - root -s /usr/bin/sh -c "java -version|grep build"
But the pipe to grep doesn't seem to work since it prints all lines regardless
java -version writes to standard error, not standard output.
su - root -s /usr/bin/sh -c "java -version 2>&1 |grep build"
2>&1 copies standard error to standard output, so that it gets fed through the pipe and into grep.
That said, grep doesn't have to be run as root, assuming the pipeline isn't being specified for use by something that just runs arbitrary code using su sh -c '...'.
su - root -s /usr/bin/sh -c 'java -version' 2>&1 | grep build
I'm writing a shell script which needs to login into the pod and execute a series of commands in a kubernetes pod.
Below is my sample_script.sh:
kubectl exec octavia-api-worker-pod-test -c octavia-api bash
unset http_proxy https_proxy
mv /usr/local/etc/octavia/octavia.conf /usr/local/etc/octavia/octavia.conf-orig
/usr/local/bin/octavia-db-manage --config-file /usr/local/etc/octavia/octavia.conf upgrade head
After running this script, I'm not getting any output.
Any help will be greatly appreciated
Are you running all these commands as a single line command? First of all, there's no ; or && between those commands. So if you paste it as a multi-line script to your terminal, likely it will get executed locally.
Second, to tell bash to execute something, you need: bash -c "command".
Try running this:
$ kubectl exec POD_NAME -- bash -c "date && echo 1"
Wed Apr 19 19:29:25 UTC 2017
1
You can make it multiline like this:
$ kubectl exec POD_NAME -- bash -c "date && \
echo 1 && \
echo 2"
The following should work
kubectl -it exec podname -- bash -c "ls && ls"
bin dev etc home proc root run sys tmp usr var bin
dev etc home proc root run sys tmp usr var
If above command doesn't work then try too replace bash with one of the following /bin/bash, sh or /bin/sh
-t
can solve your task
For example, I run here few cmd:
kubectl get pods |grep nginx|cut -f1 -d\ |\
while read pod; \
do echo "$pod writing:";\
kubectl exec -t $pod -- bash -c \
"dd if=/dev/zero of=/feeds/test.bin bs=260K count=4 2>&1|\
grep copi |cut -d, -f4; \
a=$SECONDS; echo -ne 'reading:'; cat /feeds/test.bin >/dev/null ; \
let a=SECONDS-a ; \
echo $a sec"
done
p.s. your example will be:
kubectl exec -t octavia-api-worker-pod-test -c octavia-api -- bash -c "unset http_proxy https_proxy ; mv /usr/local/etc/octavia/octavia.conf /usr/local/etc/octavia/octavia.conf-orig ; /usr/local/bin/octavia-db-manage --config-file /usr/local/etc/octavia/octavia.conf ; upgrade ; head"
Posting here because google search still brings you to this post...
I'd like to throw out using a HEREDOC as an additional possibility.
kubectl exec -i --tty-false PODNAME -- bash << EOF
echo "insert all your commands here."
echo "this subprocess will even pickup any variables you have in"
echo "the shell script that is calling this"
EOF
When using inline C with Varnish I've not been able to get /etc/varnish/default
to be happy at startup.
I've tested inline C with varnish for two things: GeoIP detection and Anti-Site-Scraping functions.
The DAEMON_OPTS always complains even though I'm following what other seem
to indicate works fine.
My problem is that this command line start up works:
varnishd -f /etc/varnish/varnish-default.conf -s file,/var/lib/varnish/varnish_storage.bin,512M -T 127.0.0.1:2000 -a 0.0.0.0:8080 -p 'cc_command=exec cc -fpic -shared -Wl,-x -L/usr/include/libmemcached/memcached.h -lmemcached -o %o %s'
But it errors out with trying to start up from default start scripts:
/etc/default/varnish has this in it:
DAEMON_OPTS="-a :8080 \
-T localhost:2000 \
-f /etc/varnish/varnish-default.conf \
-s file,/var/lib/varnish/varnish_storage.bin,512M \
-p 'cc_command=exec cc -fpic -shared -Wl,-x -L/usr/include/libmemcached/memcached.h -lmemcached -o %o %s'"
The error is:
# /etc/init.d/varnish start
Starting HTTP accelerator: varnishd failed!
storage_file: filename: /var/lib/varnish/vbox.local/varnish_storage.bin size 512 MB.
Error:
Unknown parameter "'cc_command".
If I try change the last line to:
-p cc_command='exec cc -fpic -shared -Wl,-x -L/usr/include/libmemcached/memcached.h -lmemcached -o %o %s'"
It's error is now:
# /etc/init.d/varnish start
Starting HTTP accelerator: varnishd failed!
storage_file: filename: /var/lib/varnish/vbox.local/varnish_storage.bin size 512 MB.
Error: Unknown storage method "hared"
It's trying to interpret the '-shared' as -s hared and 'hared' is not a storage type.
For both GeoIP and the Anti-Site-Scrape I've used the exact recommended daemon options
plus have tried all sorts of variations like adding ' and '' but no joy.
Here is a link to the instruction I've followed that work fine except the DAEMON_OPTS part.
http://drcarter.info/2010/04/how-fighting-against-scraping-using-varnish-vcl-inline-c-memcached/
I'm using Debian and the exact DAEMON_OPTS as stated in the instructions.
Can anyone help with a pointer on what's going wrong here?
Even if Jacob will probably never read this, visitors from the future might appreciate what I'm going to write.
I believe I know what's wrong, and it looks like a Debian-specific problem, at least verified on Ubuntu 11.04 and Debian Squeeze.
I traced the execution from my /etc/default/varnish that contains the $DAEMON_OPTS to the init script.
In the init script /etc/init.d/varnish, the start_varnishd() function is:
start_varnishd() {
log_daemon_msg "Starting $DESC" "$NAME"
output=$(/bin/tempfile -s.varnish)
if start-stop-daemon \
--start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- \
-P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1; then
log_end_msg 0
else
log_end_msg 1
cat $output
exit 1
fi
rm $output
}
So I modified it to print the full start-stop-daemon command line, like:
start_varnishd() {
log_daemon_msg "Starting $DESC" "$NAME"
output=$(/bin/tempfile -s.varnish)
+ echo "start-stop-daemon --start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- -P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1"
if start-stop-daemon \
--start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- \
-P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1; then
log_end_msg 0
So I got a command line echoed on STDOUT, and copied-pasted it into my shell. And, surprise! It worked. WTF?
Repeated again to be sure. Yes, it works. Mmh. Could it be another of those bash/dash corner cases?
Let's try feeding the start-stop-daemon command line to bash, and see how it reacts:
start_varnishd() {
log_daemon_msg "Starting $DESC" "$NAME"
output=$(/bin/tempfile -s.varnish)
if bash -c "start-stop-daemon \
--start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- \
-P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1"; then
log_end_msg 0
else
log_end_msg 1
cat $output
exit 1
fi
rm $output
}
Yes, it works just fine, at least for my case.
Here's the relevant part of my /etc/default/varnish:
...
## Alternative 2, Configuration with VCL
#
# Listen on port 6081, administration on localhost:6082, and forward to
# one content server selected by the vcl file, based on the request. Use a 1GB
# fixed-size cache file.
#
DAEMON_OPTS="-a :6081 \
-T localhost:6082 \
-f /etc/varnish/geoip-example.vcl \
-S /etc/varnish/secret \
-s malloc,100M \
-p 'cc_command=exec cc -fpic -shared -Wl,-x -L/usr/include/GeoIP.h -lGeoIP -o %o %s'"
...
I've seen posts where someone tried to work around this problem by moving the compile command into a separated shell script. Unfortunately that doesn't change the fact that start-stop-daemon is going to pass the $DAEMON_OPTS var through dash, and that will result in mangled options.
Would be something along the lines of:
-p 'cc_command=exec /etc/varnish/compile.sh %o %s'"
And then the compile.sh script as:
#!/bin/sh
cc -fpic -shared -Wl,-x -L/usr/include/GeoIP.h -lGeoIP -o $#
but it doesn't work, so just patch your init scripts, and you're good to go!
Hope you can find this information useful.
You can try using :-
DAEMON_OPTS="-a :8080 \
-T localhost:2000 \
-f /etc/varnish/varnish-default.conf \
-s file,/var/lib/varnish/varnish_storage.bin,512M \
-p cc_command='exec cc -fpic -shared -Wl,-x -L/usr/include/libmemcached/memcached.h -lmemcached -o %o %s'"
Obviously, your startup script interpreting the DAEMON_OPTS is not prepared for whitespace (even within single quotes). At my Fedora (15) installation, the suggested solution works fine; the arguments get interpreted correctly because the "$*" bash parameter is passed in /etc/init.d/varnish and in /etc/init.d/functions in daemon().
Did you get your startup scripts from a package or did you make custom scripts?
This isn't directly related to the question, but you may find yourself here if you are working through the Varnish Tutorial - Put Varnish on port 80.
For recent installs of Varnish on Debian systems the configuration for varnishd startup options can be found in /etc/systemd/system/multi-user.target.wants/varnish.service. The documented way of changing the port via /etc/default/varnish still exists, but is no longer functional unless you change your system to use init scripts rather than systemd.
After you've changed your options in /etc/systemd/system/multi-user.target.wants/varnish.service, don't forget to run systemctl daemon-reload, which will catalog the changes for executing the program.