take the hostname from /etc/host_hostname if the file is there. This … #329
Conversation
…replaces env SYSLOG_HOSTNAME when logspout is run as a global service
|
closes #328 |
adapters/syslog/syslog.go
Outdated
| pid := getopt("SYSLOG_PID", "{{.Container.State.Pid}}") | ||
|
|
||
| b, err := ioutil.ReadFile("/etc/host_hostname") // just pass the file name | ||
| if err != nil { |
There was a problem hiding this comment.
Should also check for empty b here.
|
@chris7444 to clarify here, "global service" means a docker service running in a swarm cluster, correct? |
|
@michaelshobbs global service means there will be one instance of the service (called a task) running on each and every docker node in the swarm. Which is a perfect fit for monitoring agents or containers like logspout. The moment you add a node in the swarm, docker will make sure one replica of the service will run on the new node. The other deployment option is "replicated" where you say I want 'N' instances of the service running in the swarm (eg 3 nginx instances). The swarm makes sure there will always be at least 3 instances of nginx running |
README.md
Outdated
| @@ -156,6 +156,44 @@ Logspout relies on the Docker API to retrieve container logs. A failure in the A | |||
| * `SYSLOG_TAG` - datum for tag field (default `{{.ContainerName}}+route.Options["append_tag"]`) | |||
| * `SYSLOG_TIMESTAMP` - datum for timestamp field (default `{{.Timestamp}}`) | |||
|
|
|||
| #### Using Logspout in a swarm | |||
|
|
|||
| In a swarm, logspout is best deployed as a global service. When running logspout with 'docker run', you can change the value of the hostname field using the SYSLOG_HOSTNAME environment variable as explained above. However, this does not work in a compose file because the value for SYSLOG_HOSTNAME will be the same for all logspout "tasks", regardless of the docker host on which they run. To support this mode of deployment, the syslog adapter will look for the file /etc/host_hostname and, if the file exists and it is not empty, will configure the hostname field with the content of this file. You can then use a volume mount to map a file on the docker hosts with the file /etc/host_hostname in the container. The sample compose file below illustrates how this can be done | |||
There was a problem hiding this comment.
nitpick: place SYSLOG_HOSTNAME and /etc/host_hostname in backticks
|
@michaelshobbs . I did the changes in README.md and yes I did test the changes in my env (pulling the image from my repo) |
|
@michaelshobbs . What is your release schedule. when can I expect to see the changes merged into your code ? Is there anything I need to do for this to happen ? |
|
@chris7444 just haven't had time to circle back. i'll try to cut a release today. otherwise this is now in master. give it about 30 minutes to show up on docker hub though |
|
@michaelshobbs @chris7444 Using this feature breaks my logs. I use a service called "logdna" to aggregate all logs. When I mount /etc/host_hostname, the host is correctly displayed but the message is truncated after. When I hardcode the hostname using SYSLOG_HOSTNAME, everything works fine. Could it be possible that reading a file with go would add some hidden character ? |
|
Probably you have a newline character, and we should strip whitespace from the file after its read. |
|
@josegonzalez There is no newline, I really don't get it. There is no weird character or anything. |
|
Any way to dump the raw content that is sent to the server ? Some kind of debug mode or something ? |
|
You're not understanding me. Your file has two lines, and we're reading the whole thing. So the output includes a newline, which is probably causing logs being shipped to be truncated. The fix is literally for something in our golang code that reads the hostname to trim all whitespace from both ends. If you want to contribute that, that would be great. |
|
Oh, you are right, I got confused because I just checked my file with |
* upstream/master: (73 commits) better log preface null toJSON on raw fix working_directory so we don't duplicate test runs pass debug to test container use alpine 3.6 to get golang 1.8.3 break out hostname setting into func and add simple test add test for host_hostname file strip \r and \n when reading the file /etc/host_hostname minor changes to README.md update README.md for swarm deployments PR gliderlabs#329 address comments PR gliderlabs#329 take the hostname from /etc/host_hostname if the file is there. This replaces env SYSLOG_HOSTNAME when logspout is run as a global service set version to dev on master set version to 3.2.3 for release update changelog fix new golint lintballs prepare 3.2.3 release Add TAIL environment variable to list of envvars review comment - single call to get tail envvar ...
using environment variable SYSLOG_HOSTNAME does not help when logspout is used as a a global service
this changes consists in looking for the file /etc/host_hostname to find the SYSLOG_HOSTNAME
typically, one will run the container with -v/etc/hostname:/etc/host_hostname
When using a compose file, the file will look like something like this
version: "3"
networks:
logging:
services:
logspout:
image: svt2-dtr.am2.cloudra.local/team/logspout:latest
environment:
- ALLOW_TTY=1
networks:
- logging
volumes:
- /etc/hostname:/etc/host_hostname:ro
- /var/run/docker.sock:/var/run/docker.sock
command:
syslog://svt2-logger.am2.cloudra.local:514
deploy:
mode: global
resources:
limits:
cpus: '0.20'
memory: 256M
reservations:
cpus: '0.10'
memory: 128M