Write logs both to stdout and to file

[partemyeva]

Hello

Is it possible to add opportunity to write logs to the file either? It seems that logrus supports logging to multiple locations from the same application: https://github.com/sirupsen/logrus/blob/b53d94c8ada4ef48988cb955795bf5c22dcf4b25/README.md#L185

The log file would be useful to configure filebeat container input for ELK integration.

Thanks

[diafour]

Hello! Best practice in Kubernetes is gather logs at node level, so every application just print logs to stdout.
There is no need to configure logrus, you can achieve "logging to multiple locations" using custom entrypoint.sh with tee command in it and give filebeat a try right now.
May be you give more details? Why you need filebeat for shell-operator only?

[partemyeva]

Perhaps we don't follow the best practice, but historically each pod contains an application container and a filebeat container.

Thank you for idea with tree command!

I'm trying to use a custom entrypoint with tee command, my Dockerfile based on shell-operator Dockerfile:

FROM flant/shell-operator:v1.0.10

RUN apk add --update --no-cache \
        curl \
    rm -f /var/cache/apk/*

ENTRYPOINT ["/sbin/tini", "--", "/shell-operator"]
CMD ["start", "|", "tee", "/opt/app/log/log.json"]

build custom docker image curl-shell-operator:0.1.1 and use it as container image in StatefulSet for custom operator

Here is rendered helm chart resources: templates.zip

Then install helm chart with these resources, but an error is logged in operator container:

shell-operator: error: unexpected |, try --help
stream closed

Am I doing something wrong?

[diafour]

Yep, it's not working that way.

Create additonal entrypoint.sh file:

#!/bin/bash

/shell-operator start | tee /opt/app/log/log.json

Add it to the image and change argument for tini:

FROM flant/shell-operator:v1.0.10

RUN apk add --update --no-cache \
        curl \
    rm -f /var/cache/apk/*

COPY entrypoint.sh /

ENTRYPOINT ["/sbin/tini", "--", "/entrypoint.sh"]

[partemyeva]

Thanks a lot for help!

Combined with unbuffer command (from expect package) it works perfect:

#!/bin/bash

unbuffer /shell-operator start | tee /opt/app/log/log.json