Open Policy Agent
Caching http.sends across different Eval()s, using the Go API
#616
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I'm trying to use OPA+Rego via the Go API in a case where I want to call out to an external API. I notice that we talk about caching of Is that expected? package main
import (
"context"
"fmt"
"log"
"time"
"github.com/open-policy-agent/opa/ast"
"github.com/open-policy-agent/opa/rego"
)
func main() {
ctx := context.Background()
// Create query that produces a single document.
r := rego.New(
rego.Query("data.example.p"),
rego.Module("example.rego",
`package example
response := http.send({
"method": "get",
"url": sprintf("https://endoflife.date/api/%s.json", [input.product]),
"cache": true,
"force_cache": true,
"force_cache_duration_seconds": 100000,
})
p = [response.status] { true }`,
))
query, err := r.PrepareForEval(ctx)
must(err)
input := ast.NewObject()
input.Insert(ast.StringTerm("product"), ast.StringTerm("nodejs"))
start := time.Now()
rs, err := query.Eval(ctx, rego.EvalParsedInput(input))
must(err)
fmt.Printf("rs[0].Expressions[0].Value: %v\n", rs[0].Expressions[0].Value)
t := time.Now()
elapsed := t.Sub(start)
fmt.Printf("elapsed: %v\n", elapsed)
// then again
start = time.Now()
rs, err = query.Eval(ctx, rego.EvalParsedInput(input))
must(err)
fmt.Printf("rs[0].Expressions[0].Value: %v\n", rs[0].Expressions[0].Value)
t = time.Now()
elapsed = t.Sub(start)
fmt.Printf("elapsed: %v\n", elapsed)
}
func must(err error) {
if err != nil {
log.Fatal(err)
}
}Example output: Rego snippetpackage example
response := http.send({
"method": "get",
"url": sprintf("https://endoflife.date/api/%s.json", [input.product]),
"cache": true,
"force_cache": true,
"force_cache_duration_seconds": 100000,
})
p = [response.status] { true }
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Replies: 1 comment 4 replies
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You'll need to pass a |
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Thank you! I've actually just debugged through the codebase and worked that out too - thank you for confirmation 🙌 We can see this now drastically improves performance 🚀 : For completeness: The changes needed: diff --git main.go main.go
index 0ef810f..ca1e67f 100644
--- main.go
+++ main.go
@@ -8,11 +8,14 @@ import (
"github.com/open-policy-agent/opa/ast"
"github.com/open-policy-agent/opa/rego"
+ "github.com/open-policy-agent/opa/topdown/cache"
)
func main() {
ctx := context.Background()
+ cache := cache.NewInterQueryCache(nil)
+
// Create query that produces a single document.
r := rego.New(
rego.Query("data.example.p"),
@@ -37,7 +40,7 @@ p = [response.status] { true }`,
input.Insert(ast.StringTerm("product"), ast.StringTerm("nodejs"))
start := time.Now()
- rs, err := query.Eval(ctx, rego.EvalParsedInput(input))
+ rs, err := query.Eval(ctx, rego.EvalParsedInput(input), rego.EvalInterQueryBuiltinCache(cache))
must(err)
fmt.Printf("rs[0].Expressions[0].Value: %v\n", rs[0].Expressions[0].Value)
@@ -47,7 +50,7 @@ p = [response.status] { true }`,
// then again
start = time.Now()
- rs, err = query.Eval(ctx, rego.EvalParsedInput(input))
+ rs, err = query.Eval(ctx, rego.EvalParsedInput(input), rego.EvalInterQueryBuiltinCache(cache))
must(err)
fmt.Printf("rs[0].Expressions[0].Value: %v\n", rs[0].Expressions[0].Value)
And the full code snippet: package main
import (
"context"
"fmt"
"log"
"time"
"github.com/open-policy-agent/opa/ast"
"github.com/open-policy-agent/opa/rego"
"github.com/open-policy-agent/opa/topdown/cache"
)
func main() {
ctx := context.Background()
cache := cache.NewInterQueryCache(nil)
// Create query that produces a single document.
r := rego.New(
rego.Query("data.example.p"),
rego.Module("example.rego",
`package example
response := http.send({
"method": "get",
"url": sprintf("https://endoflife.date/api/%s.json", [input.product]),
"cache": true,
"force_cache": true,
"force_cache_duration_seconds": 100000,
})
p = [response.status] { true }`,
))
query, err := r.PrepareForEval(ctx)
must(err)
input := ast.NewObject()
input.Insert(ast.StringTerm("product"), ast.StringTerm("nodejs"))
start := time.Now()
rs, err := query.Eval(ctx, rego.EvalParsedInput(input), rego.EvalInterQueryBuiltinCache(cache))
must(err)
fmt.Printf("rs[0].Expressions[0].Value: %v\n", rs[0].Expressions[0].Value)
t := time.Now()
elapsed := t.Sub(start)
fmt.Printf("elapsed: %v\n", elapsed)
// then again
start = time.Now()
rs, err = query.Eval(ctx, rego.EvalParsedInput(input), rego.EvalInterQueryBuiltinCache(cache))
must(err)
fmt.Printf("rs[0].Expressions[0].Value: %v\n", rs[0].Expressions[0].Value)
t = time.Now()
elapsed = t.Sub(start)
fmt.Printf("elapsed: %v\n", elapsed)
}
func must(err error) {
if err != nil {
log.Fatal(err)
}
} |
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Great! I think you can pass the cache to the prepared query already, but it probably doesn’t matter much. |
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I found that when doing so, it didn't seem to make a difference 😅 Not sure if it's a case that converting it to a |
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Hmm not sure, and can’t look now, but I’d look at how OPA does it. Pretty sure it’s done at that stage there? |
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You'll need to pass a
rego.InterQueryBuiltinCache()for that to happen. I'm on the move right now but I think you'll figure it out from here. If not, let me know and I can give more details later. Should be many tests around this in OPA to look at for inspiration too!