Author Archives: bullgare

Protobuf: add header parameters

They finally added it to the grpc-gateway: https://github.com/grpc-ecosystem/grpc-gateway/pull/3010/files#diff-c255ac405628aada46c25a2c9765605e9f823bc523d3739fd3fa71d4bcbf5c99. So, to use it you can just update to the version 2.14.0 or above — https://github.com/grpc-ecosystem/grpc-gateway/releases/tag/v2.14.0, and add something like this to your protofile:

        option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_operation) = {
            summary: "Create a new foo.";
            parameters: {
                headers: {
                    name: "My-Custom-Header";
                    description: "Some custom header description";
                    required: true;
                };
            };
        };

option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_operation) = {

summary: "Create a new foo.";

parameters: {

headers: {

name: "My-Custom-Header";

description: "Some custom header description";

required: true;

};

Go scheduler details

Scheduler was implemented by Dmitry Vyukov in go 1.1 and lives in runtime/proc.go. Good resources https://www.youtube.com/watch?v=-K11rY57K7k — video by Dmitry Vyukov (slides as pdf) https://www.ardanlabs.com/blog/2018/08/scheduling-in-go-part2.html — nice article by Bill Kennedy in 3 parts. Most of the images below are taken from this article. Main ideas Goroutines are very light weight (~2KB+) and very cheap …

Golang. Adding a json body to POST request in protofile

It could be a bit tricky, and I failed to find a good example for it.

How to install Outline VPN on a random VPS server

In Ountline Manager, when you add a new server, select an option called «Set up Outline everywhere».

MySQL 5.7 alter table blocking operations

Table 14.12 Online DDL Support for Column Operations

How to reinstall MacOS on M1 MacBook wiping previous admin

I’ve run into an issue when I gave my older MacBook with M1 chip to my wife. Even after reinstalling MacOS with a proper user for her and restoring from Time Machine, her admin account was not really the admin of that laptop. She was unable to create new users (MacOs failed to set a …

MySQL: generate and insert a range of dummy rows

There are a lot of ways to do this, but the one below is the most straightforward to me.

DataDog: use events in dashboards

Using events as datasource is pretty straightforward, and described here — https://docs.datadoghq.com/events/. To use it as a graph overlay (for instance, to show app deployments), you can edit your graph, Event Overlays, and add something like below:

tags:tool:morty,dd_env:$env [something like order-history-*]

1	tags:tool:morty,dd_env:$env [something like order-history-*]

Fixing docker does not want to update images

If you run docker pull, and you see an error like failed to register layer: Error processing tar file(exit status 2): fatal error: runtime: out of memory, there could be 2 reasons. Obvious one — not enough disk space for docker. You can fix it with

docker system prune -af
docker volume ls -qf dangling=true

1 2	docker system prune -af docker volume ls -qf dangling=true

WARNING: It will remove your unused resources like …

How to add and increase swap on CentOS

Adding a swap file without reboot If you are having a dedicated server somewhere with not that much memory, you could decide to add a swap without rebooting your server. To do so, you need to follow the routine:

sudo dd if=/dev/zero of=/swapfile count=1024 bs=1MiB
sudo mkswap /swapfile
sudo chmod 0600 /swapfile
sudo swapon /swapfile

sudo dd if=/dev/zero of=/swapfile count=1024 bs=1MiB

sudo mkswap /swapfile

sudo chmod 0600 /swapfile

sudo swapon /swapfile

Increasing a swap size If something goes wrong with your system, and you see that …