mohashari

#!/bin/bash
# Capture off-CPU stack traces for 30 seconds, then generate flame graph
# Requires: bpftrace, stackcollapse-bpftrace.pl, flamegraph.pl

bpftrace -e '
tracepoint:sched:sched_switch {
    if (args->prev_state == TASK_INTERRUPTIBLE || 
        args->prev_state == TASK_UNINTERRUPTIBLE) {
        @offcpu[args->prev_pid, ustack] = nsecs;
    }

mohashari

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "log"
    "strings"

    "github.com/elastic/go-elasticsearch/v8"

mohashari

package flags

import (
	"crypto/sha256"
	"encoding/binary"
	"strings"
)

type Context struct {
	UserID    string

mohashari

FROM alpine:3.19

RUN apk add --no-cache pgbouncer

COPY pgbouncer.ini /etc/pgbouncer/pgbouncer.ini
COPY userlist.txt /etc/pgbouncer/userlist.txt

RUN chown -R nobody:nobody /etc/pgbouncer

USER nobody

mohashari

func (cb *CircuitBreaker) Execute(fn func() error) error {
	cb.mu.Lock()
	state := cb.currentState()
	if state == StateOpen {
		cb.mu.Unlock()
		return ErrCircuitOpen
	}
	cb.mu.Unlock()

	err := fn()

mohashari

# Install Redis Stack (includes RedisBloom, RedisSearch, RedisJSON)
docker run -p 6379:6379 redis/redis-stack-server:latest

# Create a Bloom filter: 1M capacity, 0.1% false positive rate
redis-cli BF.RESERVE crawled_urls 0.001 1000000

# Add and test items
redis-cli BF.ADD crawled_urls "https://example.com/page-1"
redis-cli BF.EXISTS crawled_urls "https://example.com/page-1"  # returns 1
redis-cli BF.EXISTS crawled_urls "https://never-seen.com"       # returns 0

mohashari

func VersionMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        version := r.Header.Get("API-Version")
        if version == "" {
            version = "2024-01" // default to latest stable
        }

        supported := map[string]bool{
            "2023-06": true,
            "2024-01": true,

mohashari

func TenantMiddleware(store TenantStore) func(http.Handler) http.Handler {
    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            host := r.Host // e.g. "acme.app.io"
            subdomain := strings.Split(host, ".")[0]

            tenant, err := store.GetBySubdomain(r.Context(), subdomain)
            if err != nil || tenant == nil {
                http.Error(w, "tenant not found", http.StatusNotFound)
                return

mohashari

func serviceIdentityFromRequest(r *http.Request) (string, error) {
	if r.TLS == nil || len(r.TLS.PeerCertificates) == 0 {
		return "", fmt.Errorf("no client certificate presented")
	}
	cert := r.TLS.PeerCertificates[0]
	for _, uri := range cert.URIs {
		if uri.Scheme == "spiffe" {
			return uri.String(), nil
		}
	}

mohashari

version: "3.8"
services:
  zookeeper:
    image: confluentinc/cp-zookeeper:7.5.0
    environment:
      ZOOKEEPER_CLIENT_PORT: 2181

  kafka:
    image: confluentinc/cp-kafka:7.5.0
    depends_on: [zookeeper]