fix(proxy-injector): handle proxy-log-level with quotes

[olix0r]

The proxy accepts log filters in the form target[fields...]=level, where a
field may include a value match. This leads to log filters like
linkerd[name="outbound"]=debug.

When a log filter is configured via annotation or Helm, the proxy-injector fails
to properly quote the log environment variable, leading to a failure to patch
resources properly.

To fix this, this change ensures that the log level is quoted, which properly
escapes any quotes in the filter itself.

[adleong]

For my education, can you give an example of an incorrectly quoted value generated by the old code and then what a properly quoted value generated by the new code looks like?

[olix0r]

@adleong

For my education, can you give an example of an incorrectly quoted value generated by the old code and then what a properly quoted value generated by the new code looks like?

linkerd2/controller/proxy-injector/fake/data/pod-inject-enabled-log-level.yaml

Lines 6 to 7 in b35fa5f

	annotations:
	config.linkerd.io/proxy-log-level: linkerd[name="inbound"]=trace,linkerd[name="outbound"]=debug,info

should render as:

linkerd2/controller/proxy-injector/fake/data/pod-log-level.json

Line 155 in b35fa5f

"value": "linkerd[name=\"inbound\"]=trace,linkerd[name=\"outbound\"]=debug,info,[{headers}]=off,[{request}]=off"

Without the fix, the generated yaml from

linkerd2/charts/partials/templates/_proxy.tpl

Line 37 in c16f08c

value: "{{.Values.proxy.logLevel}}{{ if not (eq .Values.proxy.logHTTPHeaders "insecure") }},[{headers}]=off,[{request}]=off{{ end }}"

renders as:

value: "linkerd[name="inbound"]=trace,linkerd[name="outbound"]=debug,info,[{headers}]=off,[{request}]=off"

This isn't valid YAML.

:; yq . <<EOF
value: "linkerd[name="inbound"]=trace,linkerd[name="outbound"]=debug,info,[{headers}]=off,[{request}]=off" 
EOF
Error: bad file '-': yaml: did not find expected key

We need to use quote to escape the inner quotes.

:; yq . <<EOF
value: "linkerd[name=\"inbound\"]=trace,linkerd[name=\"outbound\"]=debug,info,[{headers}]=off,[{request}]=off"
EOF
value: "linkerd[name=\"inbound\"]=trace,linkerd[name=\"outbound\"]=debug,info,[{headers}]=off,[{request}]=off"