Adapt Dockerfile for arguments + multi-stage build

[jstoja]

Hello,

I saw on your issue prometheus/snmp_exporter#120 that you created this Dockerfile.
I modified it so it's lighter (using multi-stage builds), but also configurable like @brian-brazil advised it.
In addition I used the idea from prometheus/snmp_exporter#223 to statically compile it.

I hope it'll help and maybe integrate it later to the original repo!

[ninoabbate]

Hey @jstoja, could you please update the readme too? Thanks

[jstoja]

With pleasure, what do you want me to modify?
The Docker image is working the same way. The multi-stage build is totally transparent and don't change how the image is built or ran.

[ninoabbate]

The docker image is working, though the paths are different, I tested a build using the paths in README and this is the result:

$ docker run --rm -v "$PWD/mibs:/root/.snmp/mibs" \
> -v "$PWD/generator.yml:/root/go/src/github.com/prometheus/snmp_exporter/generator/generator.yml" \
> -v "$PWD/snmp.yml:/root/go/src/github.com/prometheus/snmp_exporter/generator/snmp.yml" 4e3487ca49d3
time="2018-01-16T10:38:44Z" level=info msg="Loading MIBs from $HOME/.snmp/mibs:/usr/share/snmp/mibs" source="net_snmp.go:109"
time="2018-01-16T10:38:44Z" level=warning msg="NetSNMP reported 3182 parse errors" source="main.go:72"
time="2018-01-16T10:38:44Z" level=info msg="Generating config for module default" source="main.go:30"
time="2018-01-16T10:38:44Z" level=fatal msg="Cannot find oid 'sysUpTime' to walk" source="tree.go:155"

As you see the paths are different, this is why I asked you to update the README to reflect your changes :).
Thanks again for your help.

[jstoja]

Hello @ninoabbate sorry for the delay.

I indeed need to fix the README file, but the error you're having doesn't come from that.
The MIBs you're adding from this repository, do not have the definition for sysUpTime, therefore, after testing the $HOME/mibs directory, the usual fallback is the host definition. For this to work, it's needed to have the snmp library installed (or to mount them).
For example:

• On debian, it's the libsnmp-base package: https://packages.debian.org/jessie/all/libsnmp-base/filelist
• On Alpine it's net-snmp-base: https://pkgs.alpinelinux.org/contents?branch=edge&name=net-snmp-libs&arch=x86_64&repo=main
• Sadly, for Busybox (which is the choice of Prometheus dev team), there is no package manager, therefore, no clean way to install this.

From there, 2 solutions:

• We let it like this and advise people to mount the MIBs from their host.
• We use Alpine in the Dockerfile to have the library.

Tell me which solution you prefer so I can push it + the README modification.
Thanks

[ninoabbate]

Hi @jstoja no worries, thanks!
Regarding the MIBs included in this repo, they are all recognized, infact if you run the container as explained in the current README everything works:

$ docker run --rm -v "$PWD/mibs:/root/.snmp/mibs" \
> -v "$PWD/generator.yml:/root/go/src/github.com/prometheus/snmp_exporter/generator/generator.yml" \
> -v "$PWD/snmp.yml:/root/go/src/github.com/prometheus/snmp_exporter/generator/snmp.yml" aabbate/secg:v0.8.0
time="2018-01-26T17:08:34Z" level=info msg="Loading MIBs from $HOME/.snmp/mibs:/usr/share/snmp/mibs" source="net_snmp.go:109"
time="2018-01-26T17:08:34Z" level=warning msg="NetSNMP reported 5 parse errors" source="main.go:72"
time="2018-01-26T17:08:34Z" level=info msg="Generating config for module default_ifname" source="main.go:30"
time="2018-01-26T17:08:34Z" level=info msg="Generated 42 metrics for module default_ifname" source="main.go:33"
time="2018-01-26T17:08:34Z" level=info msg="Generating config for module default_ifindex" source="main.go:30"
time="2018-01-26T17:08:34Z" level=info msg="Generated 42 metrics for module default_ifindex" source="main.go:33"
time="2018-01-26T17:08:34Z" level=info msg="Generating config for module paloalto_fw" source="main.go:30"
time="2018-01-26T17:08:34Z" level=info msg="Generated 152 metrics for module paloalto_fw" source="main.go:33"
time="2018-01-26T17:08:34Z" level=info msg="Generating config for module default" source="main.go:30"
time="2018-01-26T17:08:34Z" level=info msg="Generated 42 metrics for module default" source="main.go:33"
time="2018-01-26T17:08:34Z" level=info msg="Config written to snmp.yml" source="main.go:57"

We can include the package net-snmp-base and I'm cool with that, but keep in mind that the goal of this container is to make easy to everyone to create by himself the SNMP exporter configuration for monitoring their own devices starting from their MIBs, so they indeed will need to mount their MIBs, the fact that there are included MIBs in this repo is only for demo purposes .