Plugin: Migrate to @grpc/grpc-js to resolve problems when IPv6 is disabled

[aknuds1]

Migrate to @grpc/grpc-js, in order to solve #48, since the IPv6 issue is presumably not present in the pure-JS version of gRPC.

I had to make a lot of changes because of TypeScript compilation errors that appeared, I can only guess that grpc-js has stricter type definitions. In particular, I had to move gRPC methods out of classes, because the class types didn't have the right interface.

In retrospect, I think I might understand how to give the class types the right interface (basically make them indexable by string), so I could probably re-introduce classes for containing the methods.

Fixes #48

NB:
How should I best test this? I tested it manually, by rendering a panel in Grafana and it does work.

[marefr]

Works with Ubuntu 16.04 with both Grafana 6.7.x and 7.0.x. Still need to figure out how to disable IPv6 and test again.

[marefr]

Tried disable IPv6 using these instructions:

# create the long-life config file
echo "net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1" | sudo tee /etc/sysctl.d/99-my-disable-ipv6.conf

# ask the system to use it
sudo service procps reload

# check the result
cat /proc/sys/net/ipv6/conf/all/disable_ipv6

Can still run the v1.0.12 version of image renderer plugin. Not sure what else to do?

[marefr]

Was able to turn off IPv6 completely using a boot option (instructions)

• Couldn't start v1.0.12 on v6.7.x (should be due to IPv6 disabled).
• Can run this branch on v6.7.x and 7.0.x 👍

[aknuds1]

Was able to turn off IPv6 completely using a boot option (instructions)

• Couldn't start v1.0.12 on v6.7.x (should be due to IPv6 disabled).
• Can run this branch on v6.7.x and 7.0.x +1

@marefr Yayyy

[marefr]

Since we're upgrading zeit/pkg need to verify these changes works on Windows and Darwin as well - had issues with that earlier.

[marefr]

Verified works on Windows. Who can help out testing this on Darwin?

[aknuds1]

@marefr I can do that.

[aknuds1]

I tested it on OS X @marefr, works.

[marefr]

LGTM

Added a minor change that would be nice before merging

[towolf]

Thanks @aknuds1! Great work.