contrib/bradfitz/gomemcache: trace the processing keys

[mingrammer]

Hi.

Currently, the memcached tracer is just creating a span and does not trace anything except env tag. So, dashboard shows only env variable, and I couldn't find any valuable information such as processing keys.

It would be nice to add the keys tag for tracking the used key for each memcached operations. If you agree with this, I can make a PR for this.

[gbbr]

Hi @mingrammer!

I'm not sure exactly what you mean here. Can you please try to explain in a different way for me? Maybe post a screenshot of what you're seeing and explain what you're not seeing? Specifically the part where you say:

does not trace anything except env tag. So, dashboard shows only env variable

...is unclear to me

[mingrammer]

Here are two screenshots, one is for redis, other is for memcached.

Redis in APM

It shows various information such as executed command (including used keys), current db and so on.

Memcached in APM

But the memcached span shows only env tag. I want to track keys used in a memcached operation as in the redis span.

[gbbr]

Thanks for doing this! That makes complete sense now! I think it should be fine to make this change and add more tags as long as it doesn't reveal any sensitive information!

[mingrammer]

Thank you. I’ll send a PR for adding some tags to memcached span.

[knusbaum]

Hi, @mingrammer. I have reopened this issue since we had to revert #642.

We can take another look at this issue and come up with another solution.

Including all keys and values in particular was the issue. We can talk about your use case more to understand what a good solution might be.

[knusbaum]

Closing this for now.

Please reopen if we need to revisit this.