Tame cloud complexity with F# powered DSLs (build stuff)
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The emergence of Cloud platforms has fundamentally changed the IT landscape. However, attempting to ride on this ever-expanding platform ecosystem wave has created a new set of challenges. Join Yan Cui in this talk as he draws on his extensive experience with AWS over the last 7 years to illustrate, with real-world use examples, how you can use F# to build internal and external DSLs to tame the complexity from these cloud services.
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Tame cloud complexity with F# powered DSLs (build stuff)
- 1. tame |> (cloud <| complexity) |> with |> (fsharp >> powered >> DSLs)
- 2. hi,I’mYanCui
- 6. AWS user since 2009
- 8. image by nerovivo license : https://creativecommons.org/licenses/by-sa/2.0/
- 21. can be changed on-the-fly
- 23. infinitely scalable (but you still have to pay for it)
- 26. Query: given a hash key filter on range key, or local secondary index
- 28. Hash Key Range Key Local Secondary Index Global Secondary Index
- 29. Scan: FULL TABLE search (performance + cost concern)
- 31. Hash Key Range Key Local Secondary Index Global Secondary Index
- 32. Hash Key Range Key Local Secondary Index Who are the TOP 3 players in “Starship X” with a score of at least 1000? Global Secondary Index
- 34. select GameTitle, UserId, TopScore from GameScores where GameTitle = “Starship X” and TopScore >= 1000 order desc limit 3 with (NoConsistentRead, Index(GameTitleIndex, true))
- 38. GOAL SELECT UserId, TopScore FROM GameScore WHERE GameTitle CONTAINS “Zelda” ORDER DESC LIMIT 3 WITH (NoConsistentRead)
- 40. F# & FParsec* *www.quanttec.com/fparsec External DSL via
- 42. SELECT * FROM GameScore Abstract Syntax Tree (AST) FParsec
- 43. SELECT * FROM GameScore keyword keyword * | attribute, attribute, … table name
- 44. SELECT * FROM GameScore type Attributes = | Asterisk | Attributes of string[]
- 45. SELECT * FROM GameScore type Query = { Attributes : Attributes Table : string }
- 46. SELECT * FROM GameScore Parser for “SELECT” keyword pSelect
- 47. SELECT * FROM GameScore pSelect let pSelect = skipStringCI "select"
- 48. SELECT * FROM GameScore pSelect let pSelect = skipStringCI "select" matches the string “select” (Case Insensitive) and ignores it
- 49. SELECT * FROM GameScore pFrom let pFrom = skipStringCI "from"
- 50. SELECT * FROM GameScore Parser for a string that represents the table name pTableName
- 51. SELECT * FROM GameScore pTableName let isTableName = isLetter <||> isDigit let pTableName = many1Satisfy isTableName
- 52. SELECT * FROM GameScore pTableName let isTableName = isLetter <||> isDigit let pTableName = many1Satisfy isTableName
- 53. SELECT * FROM GameScore pTableName let isTableName = isLetter <||> isDigit let pTableName = many1Satisfy isTableName
- 54. SELECT * FROM GameScore pTableName let isTableName = isLetter <||> isDigit let pTableName = many1Satisfy isTableName
- 55. SELECT * FROM GameScore pTableName let isTableName = isLetter <||> isDigit let pTableName = many1Satisfy isTableName parses a sequence of one or more chars that satisfies the predicate function
- 56. SELECT * FROM GameScore pAsterisk * pAttributeName UserId, GameTitle, TopScore, …
- 57. SELECT * FROM GameScore pAsterisk * pAttributeName UserId, GameTitle, TopScore, … let pAsterisk = stringCIReturn "*" Asterisk
- 58. SELECT * FROM GameScore pAsterisk * pAttributeName UserId, GameTitle, TopScore, … let pAsterisk = stringCIReturn "*" Asterisk matches the specified string and return the given value
- 59. SELECT * FROM GameScore pAsterisk * pAttributeName UserId, GameTitle, TopScore, … let isAttributeName = isLetter <||> isDigit let pAttributeName = many1Satisfy isAttributeName
- 60. SELECT * FROM GameScore UserId, GameTitle, TopScore, … pAttributeName pCommapAsterisk * let pComma = skipStringCI ","
- 61. SELECT * FROM GameScore UserId, GameTitle, TopScore, … pAttributeName pCommapAsterisk * let pAttributeNames = sepBy1 pAttributeName pComma
- 62. SELECT * FROM GameScore UserId, GameTitle, TopScore, … pAttributeName pCommapAsterisk * let pAttributeNames = sepBy1 pAttributeName pComma parses one or more occurrences of pAttributeName separated by pComma
- 63. SELECT * FROM GameScore UserId, GameTitle, TopScore, … pAttributeName pComma sepBy1 pAttributeNames pAsterisk *
- 64. SELECT * FROM GameScore pAsterisk * pAttributeNames UserId, GameTitle, TopScore, …
- 65. SELECT * FROM GameScore pAsterisk * pAttributeNames UserId, GameTitle, TopScore, … let pAttribute = pAsterisk <|> pAttributeNames
- 66. SELECT * FROM GameScore pAsterisk * pAttributeNames UserId, GameTitle, TopScore, … let pAttribute = pAsterisk <|> pAttributeNames
- 67. SELECT * FROM GameScore pAsterisk * pAttributeNames UserId, GameTitle, TopScore, … choice pAttribute
- 68. SELECT * FROM GameScore pAttribute
- 69. SELECT * FROM GameScore pAttribute pTableNamepFrompSelect
- 70. SELECT * FROM GameScore pAttribute pTableNamepFrompSelect let pQuery = tuple4 pSelect pAttribute pFrom pTableName |>> (fun (_, attributes, _, table) -> { Attributes = attributes Table = table })
- 71. SELECT * FROM GameScore pAttribute pTableNamepFrompSelect let pQuery = tuple4 pSelect pAttribute pFrom pTableName |>> (fun (_, attributes, _, table) -> { Attributes = attributes Table = table })
- 72. SELECT * FROM GameScore pAttribute pTableNamepFrompSelect let pQuery = tuple4 pSelect pAttribute pFrom pTableName |>> (fun (_, attributes, _, table) -> { Attributes = attributes Table = table })
- 73. SELECT * FROM GameScore pAttribute pTableNamepFrompSelect let pQuery = tuple4 pSelect pAttribute pFrom pTableName |>> (fun (_, attributes, _, table) -> { Attributes = attributes Table = table }) Query
- 74. SELECT * FROM GameScore pAttribute pTableNamepFrompSelect tuple4 pQuery
- 76. < 50 lines of code
- 78. Recap
- 80. select GameTitle, UserId, TopScore from GameScores where GameTitle = “Starship X” and TopScore >= 1000 order desc limit 3 with (NoConsistentRead, Index(GameTitleIndex, true))
- 83. Decision Worker
- 91. Workers can run from anywhere
- 93. input = “Yan” result = “Hello Yan!” Start Finish Activity
- 95. image by Ryan Hageman license : https://creativecommons.org/licenses/by-sa/2.0/
- 97. API
- 101. – Kris Jordan “Good simplicity is less with leverage, not less with less. Good simplicity is complexity disguised, not complexity denied.”
- 105. the workflow is implied by decision worker logic…
- 106. instead..
- 107. the workflow should drive decision worker logic
- 108. the workflow should driveautomate decision worker logic
- 111. GOAL Code that matches the way you think
- 120. input result
- 122. Recap
- 129. wanna find correlations? you can DIY it! ;-)
- 130. “what latencies spiked at the same time as payment service?”
- 132. Find metrics whose 5 min average exceeded 1 second during last 12 hours
- 133. cloudWatch.Select( unitIs “milliseconds” + average (>) 1000.0 @ last 12 hours |> intervalOf 5 minutes)
- 134. cloudWatch.Select(“ unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes”)
- 135. “did any cache nodes’ CPU spike yesterday?”
- 136. cloudWatch.Select( namespaceLike “elasticache” + nameLike “cpu” + max (>) 80.0 @ last 24 hours |> intervalOf 15 minutes)
- 137. cloudWatch.Select( namespaceLike “elasticache” + nameLike “cpu” + max (>) 80.0 @ last 24 hours |> intervalOf 15 minutes) Regex
- 141. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes
- 142. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes Filters
- 143. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes TimeFrame
- 144. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes Period
- 145. type Query = { Filter : Filter TimeFrame : TimeFrame Period : Period option }
- 147. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes
- 148. type MetricTerm = Namespace | Name type Filter = | MetricFilter of MetricTerm * (string -> bool)
- 149. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes
- 150. type MetricTerm = Namespace | Name type Unit = | Unit type Filter = | MetricFilter of MetricTerm * (string -> bool) | UnitFilter of Unit * (string -> bool)
- 151. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes
- 152. type MetricTerm = Namespace | Name type Unit = | Unit type StatsTerm = | Average | Min | Max | Sum | SampleCount type Filter = | MetricFilter of MetricTerm * (string -> bool) | UnitFilter of Unit * (string -> bool) | StatsFilter of StatsTerm * (float -> bool)
- 153. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes
- 154. type MetricTerm = Namespace | Name type Unit = | Unit type StatsTerm = | Average | Min | Max | Sum | SampleCount type Filter = | MetricFilter of MetricTerm * (string -> bool) | UnitFilter of Unit * (string -> bool) | StatsFilter of StatsTerm * (float -> bool) | CompositeFilter of Filter * Filter
- 155. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes
- 156. type TimeFrame = | Last of TimeSpan | Since of DateTime | Between of DateTime * DateTime
- 157. namespaceIs ‘JustEat’ and nameLike ‘cpu’ and unitIs ‘milliseconds’ and average > 1000.0 duringLast 12 hours at intervalOf 5 minutes
- 158. type Period = | Period of TimeSpan
- 159. type Query = { Filter : Filter TimeFrame : TimeFrame Period : Period option }
- 160. Active Patterns a primer on
- 161. allow patterns to be abstracted away into named functions
- 162. Single-Case Patterns
- 163. let (|Float|) input = match Double.TryParse input with | true, n -> n | _ -> failwithf “not a float [%s]” input
- 164. let (|Float|) input = match Double.TryParse input with | true, n -> n | _ -> failwithf “not a float [%s]” input
- 165. let (|Float|) input = match Double.TryParse input with | true, n -> n | _ -> failwithf “not a float [%s]” input Float : string -> float
- 166. match someString with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x
- 167. let (|Float|) input = match Double.TryParse input with | true, n -> n match someString with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x
- 168. let (|Float|) input = match Double.TryParse input with | true, n -> n match someString with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x
- 169. match someString with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x let (|Float|) input = match Double.TryParse input with | true, n -> n
- 170. match someString with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x let (|Float|) input = match Double.TryParse input with | true, n -> n
- 171. match “42” with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x
- 172. match “boo” with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x Error!!!
- 173. Partial Patterns
- 174. let (|Float|_|) input = match Double.TryParse input with | true, n -> Some n | _ -> None
- 175. let (|Float|_|) input = match Double.TryParse input with | true, n -> Some n | _ -> None Float : string -> float option
- 176. match “boo” with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x | _ -> “not a float”
- 177. match “boo” with | Float 42.0 -> “ftw” | Float 11.0 -> “palprime” | Float x -> sprintf “just %f” x | _ -> “not a float”
- 178. Multi-Case Patterns
- 179. let (|Prime|NotPrime|NaN|) input = match Double.TryParse input with | true, n when isPrime n -> Prime n | true, n -> NotPrime n | _ -> NaN
- 180. let (|Prime|NotPrime|NaN|) input = match Double.TryParse input with | true, n when isPrime n -> Prime n | true, n -> NotPrime n | _ -> NaN
- 181. let (|Prime|NotPrime|NaN|) input = match Double.TryParse input with | true, n when isPrime n -> Prime n | true, n -> NotPrime n | _ -> NaN
- 182. let (|Prime|NotPrime|NaN|) input = match Double.TryParse input with | true, n when isPrime n -> Prime n | true, n -> NotPrime n | _ -> NaN
- 183. let (|Prime|NotPrime|NaN|) input = match Double.TryParse input with | true, n when isPrime n -> Prime n | true, n -> NotPrime n | _ -> NaN
- 184. match someString with | Prime n -> … | NotPrime n -> … | NaN -> …
- 185. match someString with | Prime n & Float 11.0 -> … | Prime n -> … | Float 42.0 | Float 8.0 -> … | NotPrime n -> … | NaN -> …
- 186. match someString with | Prime n & Float 11.0 -> … | Prime n -> … | Float 42.0 | Float 8.0 -> … | NotPrime n -> … | NaN -> …
- 187. match someString with | Prime (IsPalindrome n) -> … | Prime (IsEven n) -> … | _ -> …
- 188. Tokenise (string -> string list)
- 189. [ “namespaceIs”; “‘JustEat’”; “and”; “nameLike”; “‘cpu’”; “and”; … ]
- 190. “namespaceIs” “and” … F# List = LinkedList “‘JustEat’”
- 191. “namespaceIs” “and” … F# List = LinkedList “namespaceIs” “‘JustEat’” “and”:::: :: tail cons (::) operator to prepend “‘JustEat’”
- 192. “namespaceIs” “and” … F# List = LinkedList “namespaceIs” “‘JustEat’” “and”:::: :: tail match aList with | “‘JustEat’” works as a pattern too!
- 193. let (|StringCI|_|) (str : string) (input : string) = if str.ToLower() = input.ToLower() then Some () else None let (|Float|_|) input = match System.Double.TryParse input with | true, n -> Some n | _ -> None
- 194. let (|EmptyString|_|) input = if String.IsNullOrWhiteSpace input then Some () else None let (|StartsWith|_|) char (input : string) = if input.[0] = char then Some () else None let (|EndsWith|_|) char (input : string) = if input.[input.Length-1] = char then Some () else None
- 195. let (|QuotedString|_|) (input : string) = match input with | EmptyString -> None | str when str.Length < 2 -> None | StartsWith ''' & EndsWith ''' -> Some <| input.Substring(1, input.Length - 2) | _ -> None
- 196. let (|QuotedString|_|) (input : string) = match input with | EmptyString -> None | str when str.Length < 2 -> None | StartsWith ''' & EndsWith ''' -> Some <| input.Substring(1, input.Length - 2) | _ -> None
- 197. let (|NamespaceIs|_|) = function | StringCI “NamespaceIs" :: QuotedString ns :: tl -> Some (eqFilter MetricFilter Namespace ns, tl) | _ -> None
- 198. let (|NamespaceIs|_|) = function | StringCI “NamespaceIs" :: QuotedString ns :: tl -> Some (eqFilter MetricFilter Namespace ns, tl) | _ -> None namespaceIs ‘JustEat’ and nameLike ‘cpu’ and …
- 199. let (|NamespaceIs|_|) = function | StringCI “NamespaceIs" :: QuotedString ns :: tl -> Some (eqFilter MetricFilter Namespace ns, tl) | _ -> None “namespaceIs” “‘JustEat’” :::: …
- 200. let (|NamespaceIs|_|) = function | StringCI “NamespaceIs" :: QuotedString ns :: tl -> Some (eqFilter MetricFilter Namespace ns, tl) | _ -> None type MetricTerm = Namespace | Name type Filter = | MetricFilter of MetricTerm * (string -> bool)
- 201. let (|NamespaceIs|_|) = function | StringCI “NamespaceIs" :: QuotedString ns :: tl -> Some (eqFilter MetricFilter Namespace ns, tl) | _ -> None “and” :: “nameLike” :: “‘cpu’” :: “and” :: …
- 202. let rec loop acc = function | NamespaceIs (filter, tl) | NamespaceLike (filter, tl) | NameIs (filter, tl) | NameLike (filter, tl) | UnitIs (filter, tl) | Average (filter, tl) | Sum (filter, tl) | Min (filter, tl) | Max (filter, tl) | SampleCount (filter, tl) -> match tl with | And tl -> loop (filter::acc) tl | _ -> flatten (filter::acc), tl | _ -> failwith “No filters?!?!?”
- 203. let rec loop acc = function | NamespaceIs (filter, tl) | NamespaceLike (filter, tl) | NameIs (filter, tl) | NameLike (filter, tl) | UnitIs (filter, tl) | Average (filter, tl) | Sum (filter, tl) | Min (filter, tl) | Max (filter, tl) | SampleCount (filter, tl) -> match tl with | And tl -> loop (filter::acc) tl | _ -> flatten (filter::acc), tl | _ -> failwith “No filters?!?!?”
- 204. let rec loop acc = function | NamespaceIs (filter, tl) | NamespaceLike (filter, tl) | NameIs (filter, tl) | NameLike (filter, tl) | UnitIs (filter, tl) | Average (filter, tl) | Sum (filter, tl) | Min (filter, tl) | Max (filter, tl) | SampleCount (filter, tl) -> match tl with | And tl -> loop (filter::acc) tl | _ -> flatten (filter::acc), tl | _ -> failwith “No filters?!?!?”
- 205. let rec loop acc = function | NamespaceIs (filter, tl) | NamespaceLike (filter, tl) | NameIs (filter, tl) | NameLike (filter, tl) | UnitIs (filter, tl) | Average (filter, tl) | Sum (filter, tl) | Min (filter, tl) | Max (filter, tl) | SampleCount (filter, tl) -> match tl with | And tl -> loop (filter::acc) tl | _ -> flatten (filter::acc), tl | _ -> failwith “No filters?!?!?”
- 206. let rec loop acc = function | NamespaceIs (filter, tl) | NamespaceLike (filter, tl) | NameIs (filter, tl) | NameLike (filter, tl) | UnitIs (filter, tl) | Average (filter, tl) | Sum (filter, tl) | Min (filter, tl) | Max (filter, tl) | SampleCount (filter, tl) -> match tl with | And tl -> loop (filter::acc) tl | _ -> flatten (filter::acc), tl | _ -> failwith “No filters?!?!?”
- 207. let parse (input : string) = input |> tokenize |> parseFilter |> parseTimeFrame |> parsePeriod
- 208. Amazing F# =
- 209. usable from anywhere you can run F# code e.g. F# REPL, executable, .. Internal DSL
- 210. useful for building tools e.g. CLI, … External DSL
- 214. Recap